Hello Roi!
No worry! This warning means you have either a theme component or a plugin that uses an old font-awesome icon name. You have nothing to do; it’s up to the authors to update their plugins/components.
Discourse recently migrated Fontawesome from v5 to v6; a few names must be renamed. In your case, I looked at your forum and saw map-marker-alt (new name is location-dot). It’s likely from Locations Plugin.